


Half brother

by miss_fireworks



Category: Haikyuu!!
Genre: M/M
Language: English
Status: In-Progress
Published: 2020-05-29
Updated: 2020-11-07
Packaged: 2021-03-03 01:41:12
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 4,766
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24436828
Author URL: https://archiveofourown.org/users/miss_fireworks/pseuds/miss_fireworks
Summary: - His name is Yukio, Yukio Oikawa.- ...What?( Or Kageyama's mother and Oikwa's father are together and decide to move in together.  Might as well say that they won't like it)
Relationships: Kageyama Tobio/Oikawa Tooru, Other minor relationship - Relationship
Comments: 25
Kudos: 151





	1. Chapitre1

**Author's Note:**

> This chapter is a bit like a prologue so don't worry, the other chapters will be longer(Normally)

It was a day like any other, he woke up, went to high school, played volleyball with his team and went home. It was an absolutely normal day, an ordinary day that started and ended just like any ordinary day. At least that's what Kageyama thought when he came home that day. But when he opened the door, he found his mother sitting on the couch, at that hour she should have been at work, it was weird. She seemed slightly nervous, as if she was dreading the moment he would come home. His mother was always smiling and in a good mood, it was strange to see her like that.

\- Is everything okay, mom? He asked. 

\- Ah Tobio, you're home. Looks like she just noticed him.

\- Is everything ok? He repeated his slightly worried question.

\- Yes, everything's fine, don't worry, just... I have something to tell you, please come and sit down.

He joined her and it was his turn to be nervous, his mother never took such a serious tone even when she told him her father's death when he was eight, she always knew how to tell him calmly even if the news was awful...so he couldn't help swallowing while sitting down.

\- What's going on?

\- Well, I have some good news and some bad news, but before I tell you, I want you to know that if you don't approve, I could always change my mind because you are the most important thing to me and I want you to be happy before anyone else.

\- Is it really that bad? And why isn't Yume here?

\- Yume is too little to understand this kind of thing, she's only seven years old for her almost nothing will change.

\- I don't see what you're getting at.

\- Let's say... She couldn't find the words. I've been seeing someone for a while now. She raised her head slightly as if she was afraid of how she'd react. But for Kageyama it was really good news, for all of us there was even thinking, her mother was much happier lately for her greatest happiness. She had been alone for so long. Kageyama couldn't see how he could blame her.

\- That's great mom, I'm happy for you! 

\- You are, aren't you? What a relief I was afraid you might be angry with me.

\- Why would I be mad at you?

\- I don't know... I thought you'd be mad at me for loving someone other than your father.

\- I could never blame you for that. If you're happy, that's fine with me.

\- But your happiness is important to me too, so answer me honestly, would you mind moving in with him? She asked in an almost trembling voice.

\- Did she? It was the only answer Kageyama could give.

\- Well I've been seeing him for almost six months now and I... We've been talking about it for some time, but I want your opinion before I say yes.

Honestly, Kageyama didn't know what to think, leaving his house wasn't really a problem for him, he didn't particularly like him, and as long as he was with his mother and sister they all suited him. If he didn't like his mother's boyfriend he would just ignore him. But there was one issue that did concern him. 

\- Am I going to...

\- You're not changing schools, don't worry. She obviously planned for him to ask that question.

\- Then I'm fine with it. 

\- Is it? Really? I'm so glad.

\- But... what's the bad news? 

\- The bad news? I thought moving in with a stranger would be bad news for you. But if it's not, there's no bad news.

\- Well, that's good. When are we moving in with them?

\- Next weekend. That's not too soon for you, is it? 

\- No, it's fine. Actually, Mom?

\- Yes?

\- What's your new boyfriend's name? 

\- Oh yeah, sorry, I didn't even tell you. 

\- That's okay. 

\- His name is Yukio, Yukio Oikawa.

\- ...Wath?


	2. Chapter 2

**Notes for the Chapter:**

> English is not my mother tongue so there are probably some spelling mistakes and I apologize...but I hope you'll still enjoy this new chapter !!!

Something wrong, Tobio? 

Oh yeah...he had never told his mother about the problems he had with Oikawa in high school and that's why she was so intrigued that he chose Karasuno instead of Seijho. So she couldn't have known the tornado of thoughts that were pouring into Kageyama's head right now. Oikawa hated him, he hated him! He could never live under the same roof, he was going to be murdered ! But his mother looked so happy, it would be selfish to refuse for a simple rivalry between teenagers (rivalry that was surely going to cause his death in the next few days).

\- No, Mom, we're all fine. Is there anything else you want to tell me about it? 

\- Well, it turns out he doesn't have enough room for you and Yume, so she'll sleep with Yukio's youngest daughter and you'll sleep with her eldest son while he sets up a room for you. You don't mind?

Kageyama almost fainted.

After that day, Kageyama was just thinking about the weekend that was coming up way too fast for his taste. To say he was stressed was an understatement. You could even say he was a little scared. He didn't show it to his mother or sister of course, but the fact that he would soon be living with his worst enemy for an indefinite period of time didn't leave his mind. He was even less attentive in class and even at training sessions, he was missing too many passes compared to usual which ended up worrying his teammates, but he assured them that he was fine and that he was just tired because he had studied a lot for an upcoming test which reassured them. Except for Hinata, the little redhead was Kageyama's best friend and he knew full well that Kageyama would never study this late at night even if his life depended on it. 

So he decided to question him on his way home.

\- Seriously Kageyama, what's wrong? 

\- I told you I'm just tired, everything's fine.

The last person Kageyama wanted to tell the news to was Hinata. He liked that he was worried about him but if he found out who the person was going to be with he was going to share his new living space with, he'd be able to come and see him every day to make sure he didn't die including weekends which he didn't want.

\- You know as well as I do that you would never live again for a test! Besides, I went to see a guy from your class earlier and you don't have a test all week. Why did you lie to us?

He seemed really worried and maybe slightly hurt. Kageyama felt bad for lying to him while the little guy was making every effort to make sure he was okay. So he decided to tell him just a small part of the truth.

\- It's just that my mom has a boyfriend and we're moving in with him this weekend, I guess I'm a little stressed out about it.

\- Haaa I see! He was smiling again, which slightly relieved Kageyama. I understand you're stressed out about it. He said. After all it's going to be a big change for you who's been used to living with your mother and sister, and I think you need to...

And he continued to talk to her about what he needed to do about himself to relax and tell her that his mother was a really nice person and that there was no reason for her to be with someone mean. Kageyama didn't really listen to him anymore but he was happy to see that Hinata wasn't pushing the issue any further.

\- By the way, do you want some help with the move?

Fuck that.

\- No, no, it's okay. Her boyfriend's kids are already helping us out.

\- He's got kids?

He was a fucking idiot.

\- Um... yeah... maybe, I don't know, I mean, I've heard that, but I'm not sure.

\- It's cool! Maybe they're in high school, maybe you'll have half brothers or half sisters your own age! 

\- Yeah... great.

\- You don't look happy, aren't you happy? 

\- Yes, of course...well, I'm coming home tomorrow.

And he'll almost run home.

The day you dreaded it came at an incredible speed. No sooner had Kageyama started the week than he found himself in front of a stranger's house.

It was quite large and it was easy to deduce that the one called Yukio was making a lot of money if you consider that he had such a large house and was feeding both of them as children and was the only source of income for the family. Kageyama wondered how it was possible not to have an extra room in there.

His mother rang the bell and a tall man came to open the door. On the face of it, you could tell that he was an older copy of Oikawa, but he still looked much friendlier than this one. He greeted him and Yume and then turned to his sea and kissed him for far too long for Kageyama who looked away and hid Yume's eyes with his hand. He sincerely hoped that he would not have to see this show every day because it was really embarrassing.

To his great joy, Oikawa was not at home when they came in, he had to flee as far away from Kageyama as possible. On the other hand, his little sister was there, she seemed to be the same age as Yume but Kageyama wasn't sure because he hadn't seen her for very long, in fact, the little one had run upstairs as soon as she saw them. 

\- Excuse her. Say Yukio slightly embarrassed. Hiyori is very shy and she's not used to seeing people at home but I'm sure she'll get used to it and be happy to play with you. Yume nodded nervously. She wasn't very comfortable with strangers either. Yukio noticed this and told them he could go to the garden until it was all over.

\- Don't you need any help? Kageyama asked?

\- Don't worry, I'm pretty strong, you know. He answers by tapping his arm muscles.

So they went into the garden. This one was much bigger than their old one, there were a lot of children's games including a swing, which immediately attracted Yume's attention, so he asked him to help him swing on his own. She could do this on her own but she loved spending time with her brother and asked him to do something with her whenever she could. And something told Kageyama that she wasn't going to let go of him at all now that she was in unfamiliar surroundings. Not that he minded, he loved his sister. They also discovered a volleyball net and spent most of the afternoon playing. Yume had the same passion as Kageyama for the sport and she was strong enough for her age. 

Dinner time had arrived and Oikawa was still not home and Kageyama was secretly hoping that he would spend the night at a friend's house. In the meantime he had gotten to know Yukio a little bit, he was very easy to talk to, even for Kageyama who wasn't very talkative. He was a lawyer and he talked about his job for most of the dinner. Normally, Kegyama wouldn't even listen to him because he didn't care about that profession at all. But Yukio had the art of making everything a little interesting when he was the one talking. He also asked them questions about him and his sister but they both shut down at that point so he didn't go any further and just kept talking. Their mother seemed really happy that he could get along so Kageyama thought maybe it wasn't so bad, until Oikawa came back...

It was pretty late and Kegeyama had just finished washing, so he didn't dare go into Oikawa's room even though it was his room now. So he sat alone on the living room couch and stood there like an idiot. He could have stayed there for a long time if Yukio hadn't told him that he had the right to go to "his" room, he even accompanied him to her when he saw that Kegayama didn't dare to do it alone. He was really starting to like his mother's boyfriend. Once he arrived in the room he just stood at the door and didn't really dare to sit down anywhere, so he just watched. It was big, really big, it looked just like Oikawa, there were posters and pictures everywhere, it was pretty tidy too. He spotted a futon that was placed as far away from Oikawa's bed as possible, which didn't surprise Kageyama. He spent a long time in his thoughts looking at the room. He must really be somewhere else or he was just tired, because he didn't walk behind the door and he got hit by it when someone tried to open it.

It really hurt at first, but the pain was soon forgotten when he saw who had opened the door.

Oikawa.

\- What are you doing in my room? Her voice was more than icy at that level, it had a murderous tone to it.

\- Uh... he didn't know what to say. Oikwa didn't know he was living here now?

\- I'm... sleeping here?

\- Oh shit, I forgot about that...

Was it even possible to forget information like that?

\- Listen to me, just because we're living under the same roof now, I don't hate it any more, right ?

\- Um... ok 

\- Just so we're clear, you come near me, I'll kill you, you talk to me, I'll kill you, you touch my stuff, I'll slaughter you.

He sounded really, really serious.

\- Ok...is all Kageyama could say no without having a slightly shaky voice.

\- Good. Then he slammed the door shut.

And that's how his life with Oikawa Tooru started.

**Notes for the Chapter:**

> I'm waiting for your opinion !!


	3. Chapter 3

**Notes for the Chapter:**

> This chapter is a litlle short sorryyyyy and I apologize for spelling mistakes, English is not my mother tongue (｡ŏ﹏ŏ)

Contrary to what he thought, life with Oikawa was in no way different from his previous life. In fact, he hardly ever saw him, he would leave early in the morning for who knows where to go for a run and come back late at night or sometimes not at all. He probably slept at Iwaizumi's house. 

As far as he and his family were concerned, he believes that he had never seen his mother so happy so he was happy too. On the other hand his little sister worried him, she still didn't get along with my daughter from Yukio, she hadn't gotten used to her new environment at all, she often stayed in her room and it had been a while since Kageyama had seen her smile. Sometimes he even heard her crying, but said he was trying to talk to her, she would run away. 

One day, he found her in the middle of the night in the living room, staring into the emptiness. 

"Hey..." Had he must have approached her gently. 

"Oniichan? Why aren't you sleeping?" 

"I could ask you the same thing. 

"I can't sleep..." 

He hesitated to ask her why, she'd always been a bit upset before and he didn't want to force her to say anything. So instead he took her in his arms and sat her down on his lap. They stayed like that for about ten minutes and then she started talking. 

"I don't like this house." 

"I don't like it." "Why not?" 

"I don't know...I know mom's new boyfriend is nice and she's happy like this...but I miss our old house...it doesn't smell the same here...and then her daughter and son scare me..." 

He couldn't help laughing at that. 

"They scare you? Why do they scare you?" 

"She always runs away from me as if I had the plague and she has a frightening black look...and the other one when he is there, I have the impression that he wants to kill, that frightens me ! What if he hurts you?" 

Well, he has no doubt that if Oikawa had the opportunity to kill him slowly and painfully and throw his body in a ditch he would surely do it. But he couldn't say that to his sister. 

"He won't hurt me, don't worry. And for her daughter she just has to take it upon herself to adapt to you, it's not easy for her either, you know. Can you give her some time?" 

"Hmmmm okay...but I still don't like this house. " 

He sighed, she too will need time, he thought. 

He continued to talk like that for most of the night, it made him happy to see his sister finally smiling when she told him about trivial things that had happened to him at school. He felt a little guilty for not going to see her sooner, in the end she just needed someone to talk to. After a while she started to get tired. 

"Onichann, can we sleep together tonight? I don't want to go back to my room." 

"On the couch? Are you sure?" 

"Yes, I'll sleep better if I'm with you." 

Okay, now he was feeling totally guilty. 

"Okay if you want." 

"Yayyy thank you! 

And they fell asleep in each other's arms at 5:00 in the morning. He didn't doubt that they would probably be very tired the next day but it was Saturday so it was okay. 

The next day he was woken up by the sound of a phone taking a picture. He opened his eyes with difficulty and saw his mother above them with a big smile on her face. He grunted in discontent. 

"Please delete that away." 

"No way, you're way too cute." His face wrinkled a little afterwards. "But I'd like to know what time you went to bed, it's already noon." 

"Already noon," he repeated as he got up, he didn't think he would wake up so late, he didn't even get to practice volleyball like he does every morning. 

"Well, I'm going to wash up," he muttered, still not waking up. 

As he walked past the dining table he noticed something strange. 

"Why are there more plates than usual?" 

"Oh yes! I couldn't tell you since you were sleeping, Tooru's friends are coming eat here ." 

"..." 

"Tobio? 

"Tell me this is a joke..."

**Notes for the Chapter:**

> Me? Four months late? Not at all let's see ...okay I'm really sorry for this long wait, but I had a kind of phase where I didn't feel like writing anymore ...but I came back and I'll try to update as much as I can ! I promise ! I also want to say that for a while I had a lack of inspiration for this story, so if you have anything you'd like to see, don't hesitate to ask me, I'll surely do it ! (Except coal...I don't write coal) here it is ! Sorry again hihihi (ᗒᗩᗕ)


	4. Chapter 4

**Notes for the Chapter:**

> Here's another chapter that I tried to publish quickly to apologize for being late...heheh  
> English is not my mother tongue so I apologize for any spelling mistakes.

The Oikawa team was here? Was that a joke? Wait, does that mean they saw him sleeping like that? What a shame... And who else was he eating here? The world was really against him these days... 

As he climbed the stairs, he heard voices coming from his room, or rather Oikawa's room, which was his temporary room to his great misfortune. He didn't feel like going in, even if it was to get some clean things, so he took as much time as he could to take a shower while waiting for them to come down to eat and he pretended to have a stomach ache when his mother called him too. The last thing he wanted was to eat at the same table with the three people who hated him the most in the world. 

For a moment he considered going to Hinata's house for the rest of the day, his mother and sister loved him so it wouldn't be a problem, but he remembered what his sister had told him the day before, he just couldn't leave her alone with so many strangers. She came to see him very quickly and had barely crossed the threshold of the door when she said: 

"I don't like them..." 

Decidedly, this kid was complicated. 

"...And for what?" 

"They're scary, they're all very tall and they have weird hairstyles." 

She must have been referring to Kindaichi, Kageyama thought. He also thought that one day he should teach her that a person's height and hairstyle is not a reason to hate her. 

Then he thought that since neither of them wanted to see them, they should go together. 

"Tell me, Yume, do you want to go to the park?" 

"Oh yes yes yes yes !!" 

"Okay, get up, let's go." 

"Now? But Niichan you haven't eaten yet." 

"I'll buy something on the way" he replied, everything to leave this house as soon as possible. 

"Okayyy!" 

They slowly went down the stairs, checking if the team was still in the house, to his great delight, they had gone into the garden to practice so they could sneak out. Kageyama sent a message to his mother that he was taking Yume to the park and then they left as fast as they could. 

When they arrived at the place, Yume went directly to play with other children and Kageyama sat on a bench without doing anything, they had left so fast that he didn't even think to take a volleyball. What an idiot, he was good at being bored for several hours now... 

"Kageyamaaaaaa!"  
Oh! He knew that voice. 

He turned around, and saw Hinata running his little sister's heels at him.

"What are you doing there? "he asked. He looked strangely relieved. 

"I'm bringing my sister here." 

Natsu's face lit up. 

"Is Yume-chan here? Coooool!" And she ran off to join her. 

"I'm so glad I ran into you," Hinata continued. "My mother forced me to accompany Natsu here, so we can play volleyball together," he said, brandishing a ball.

"I guess so." He said as he stood up. We were really relieved to have something to do for the next few hours, plus it had been almost a day since he had practiced. 

After telling their sister that they were going to move away for a while, they started to make passes. But for the first time in his life, Kageyama could not concentrate completely. First of all, he kept asking if the Oikawa team would still be here when he came back, but he was wondering how he would survive in this house where Oikawa lived and where there would be potentially frequent visits from his entire team...it was slightly stressful. 

After a while he even started to miss his passes because he was thinking too much. This made Hinata slightly worried. Well, Kageyama never missed those passes usually. So he walked towards it, took him by force by the arm and made him sit down on the bench where he was earlier. 

"Come on, tell me everything!" He ordered. 

"Tell you what?" 

"What is not going well, obviously!" 

"What makes you say something's wrong?" 

"You've been missing all your passes for an hour!" 

"I'm just tired, that's all." 

"You didn't even yell at me when I missed!" 

"I'm tired, I'm telling you." 

"It's wrong to lie." 

"And it's wrong to meddle in matters that are none of our business." 

"I'm your friend, so if you're wrong, it's my business."  
"..." 

It was the second time in a short time that he worried Hinata and he was really starting to feel bad about it, and then it's not like he's going to be able to hide it for long anyway. (And maybe this time he wanted to tell someone).  
"My mother's new boyfriend is Oikawa's father," he said suddenly. 

"... Oikawa? ...Oikawa Tooru??" 

"Do you know any other Oikawa?" 

"No actually... I understand you're in a bad mood so... jinx." 

The word "jinx" was a euphemism. 

"Yeah, as you say." 

"I'm surprised you're still alive," he turned to him with a worried face. "Don't worry, he didn't hit you?" 

"Of course not idiot, in fact, he's hardly ever there." 

"HA! That's good! " 

"But today he invented his whole team at home." 

"Ah...I understand better why you ran away..." 

"I don't think I can survive this several times a month..." 

"Well, if you want my advice..." 

"Not really." 

"Shut up, I think ...." 

But before he could finish his sentence, Yume and Natsu came running to pick them up to tell them that they wanted to go home because she was cold, it's true that he had been here for several hours, the temperature had dropped. 

"Well it's time to go, see you Monday Kageyama!" 

"Yeah, see you Monday" 

On the way back, he felt slightly more relaxed than this morning. Maybe he was right to tell Hinata, at least he would have someone to complain to.

**Notes for the Chapter:**

> I absolutely wanted Hinata to be aware of Kageyama's problem...idk why lol


	5. Chapter 5

**Notes for the Chapter:**

> English is not my mother tongue so I apologize for a spelling mistake. (ᗒᗩᗕ)

When they returned home in the late afternoon, Kageyama was very hopeful that the team would be gone. He heard nothing when he arrived in the dining room, so he concluded that they had indeed left to his great delight. But all his hopes were dashed when he heard voices coming from the room just as he wanted to enter. Were they camping here or what? So he decided to go outside to practice until they decided to leave, but just as he started to turn around, he heard some pretty interesting things: 

"Say Oikawa, the coach asked for a friendly match against Karasuno, didn't he? When is it?" 

Oh? They were going to play against Seijho? 

"I don't know, he just made a request, he hasn't gotten an answer yet." 

"Shouldn't we still get ready? We may have won against them last time but they're pretty strong, and the little freshman duo is pretty annoying." 

He is sure he heard Oikawa grunting. 

"Don't worry, I'm sure that... Oh Kindaichi, where are you going?" 

"To the toilet ." 

Damn. He had to get away from the door fast or else... 

The door opens. 

It's too late for that. Kindaichi had barely closed the door behind him when he saw Kageyama's face wrinkled heavily. 

"Were you spying on us? 

Once the surprise passed, Kageyama frowned, too. 

"Am I not even allowed to want to enter my room?" 

"That's not your room... you've only just arrived here and you're already seeing things as King?" 

"She's mine temporarily...and don't call me that..." 

"And why not? Isn't that what you are? OU-SA-MA" 

He had a smirk on his face knowing full well that Kageyama hated the name. Then his smile was suddenly deformed into a grimace of pain. 

"Oniichan told you not to call him that, you ugly, artichoke-headed villain!" 

Oh...his little sister who had followed him without even noticing him had just kicked Kindaichi's shin with a visibly rather powerful kick. 

Kindaichi had let out a cry of pain and Kageyama thought he heard him mumble a: "dirty kid" ! 

Then voices were heard on the other side of the door. 

"Kindaichi? What's going on?" 

So without further ado, Kageyama took Yume and ran off into the garden before he got into trouble. 

They hadn't had such a big laugh in a long time. 

\---------------------------- 

A few days later, their coach told them that they would have a deal against Seijho soon. 

So they all stayed at the gym a little later that night (to the great misfortune of some, aka: Tsukishima) to find a strategy to use against Seijho in the upcoming game. And so far, they couldn't find anything that would allow them to avoid another humiliating defeat they suffered last time. And that's when Hinata had the bad idea to open her mouth and come up with a stupid idea. 

"Hey, Bakageyama, couldn't you try to find out what her strategy they are going to use? You live with Oikawa after all." 

.... Seriously ? He was going to kill him... 

"Huh? What's this all about?" Daichi asked, he looked a little worried. 

"A king living with another king?" Tsukishima laughed. "What a horrible house this must be." 

"Is that true Kageyama?" Yamaguchi asked. "Why is that?" 

"Uh... yeah my mother is in a relationship with her father, but..." 

"The great king is your brother-in-law? Too coooool," Noya exclaimed. 

"Uh... not really..." 

"He didn't hurt you? "Yachi worried. 

"Huh? No, of course not." Why did everyone think Oikawa was hitting him? 

"Luckily for him, he's touching you and I'll kill him." Menaça Sugawara. 

"...You scare Sugawara-san." 

"But then couldn't you try to sneak into his room and find some information?" Insisted Hinata. 

Kageyama glanced at her with a black look. 

"You shut up." 

"Ehhhh that's not nice! I'm just trying to find solutions to our problem." 

"You didn't have to tell my life story for that! " 

"How was I supposed to know you wouldn't tell everyone?" 

"It was so obvious! 

"No, it wasn't! 

"Yes, it was!" 

"Please both of you calm down... Kegeyama's not that bad..." Yachi said as he tried to calm them down. 

"I'm very calm! It's the other idiot who isn't!" 

And they fought like that until the end of the meeting. 

Conclusion: he never confided anything to Hinata again.

**Notes for the Chapter:**

> I feel like my chapters are too short so I'll try to make them longer next time. !!

**Author's Note:**

> I'm waiting for your opinion!


End file.
